Method of producing propellers



March- 2-3 1926. R. WISHON METHOD OF PRODUCING PROPELLERS Original Filed Jan. 6;

hams-Ma. 23,192

PATENT OFFICE.)

RALPH WISEOILOF SAN FRANCISCO, CALIFORNIA.

METHOD PRODUCING PROPEIbIJEBSl Application filed January 6; 1921, Serial No. 435,876. v Renewed October 17, 1925.

. To all whom it ma concern:

Be it known that I, RALPH WISHON, a

citizen of the United States, residing at San Francisco, in the county of San FIGIICISCO a and State of California,? have invented certain new and useful improvements in Methods of Producing Propellers, of which the following is a specification. p This invention relates to the manufacture of propellers, and finds its best application in the production of propellers for aeroplanes, although it may be used for the production of propellers for'other purposes.

The principal object of the invention is to produce a propeller with thin metal walls, preferably left hollow, and so to dispose the metal of the walls that at least each blade in itself, and referably two blades with the connecting ub portion, will constitute one integral metal structure, and one in which maximum strength is secured with minimum weight, and avoiding the use of separate parts assembled by welding, riveting, or other means, which expenence has shown to be precarious and uncertain owing to warping out of she e, breaking, disturbance of balance, and ot er efi'ects.

In carrying out the invention, a seamless tube of metal or other suitable material is 9 taken and treated to modify its circumferential dimensions between'its ends to correspond with perimeters to be insured at different points in its length, and also to vary the section of its walls in difi'erent transverse planes to correspond to differences in thickness between the leading edges and the trailing edges of the blades; the outer end or ends of the tube being treated, for instance, by spinning orequivalent process, to

I develop thereon an integral closure or 010- 4 sures; and the intermediate portion of the tube (when two blades arevmade integral, or the inner end of the tube when the blades are made so arate) being fashioned to'develop a suita le hub portion, or to adapt the blades for assembl with a hub, as the-ease may be. hub portion as an integral structure, which is preferred, and by which the advantages 0 of the invention are most fully realized, the metal which is to ultimately constitute front and rear faces of the propeller is displaced inwardly in a manner to provide a ublining to receive a shaft or a bushitlgig through which the propeller is connect, with its shah. a

In making both blades and the In addition to these general features characterizing the method of procedure and the resultant propeller, certain special features or steps in the procedure are hereinafter taught, whereby the described changes in wall section may be developed symmetrically and with accuracy, and with uniformity in the two blades so that perfect balance is assured; also where the walls may be ultimately developed with certainty and to a smooth form and accurate outline.

Anillust-rative procedure embodying the features of the invention will now'be described in detail.

In the accom anying drawings Figures 1 an 2 are, respectively, a cross sectionand a longitudinal section of a steel tube which is used as a blank in making a propeller in accordance with the present inventlon. c

Figure 3 shows the blank after treatment to vary its circumferential dimensions.

Figure 4 shows the same blankafter its ends have been closed.

Figure 5 is a detail view representing the step of developing the hub. v Figure 6 shows theblank after it has been dressed to ta er the thickness of'its walls, both longitu inally of the blank and circumferentially of various transverse sections thereof.

Figures 6 to 6, inclusive, are sections taken, respectively, on the lines-a, a, to f, f, inclusive, of Figure 6. Figure 7 represents the final step of truing the propeller by internal hydraulic pressure while the propeller is confined in the accurately formed cavity of a heavy metal mold; and

Figure 8 represents the finished article. Numerous attem ts have been made to produce propellers For aeroplanes from steel, but these have generally involved the use of pieces of sheet steel formed into the desired shapes, with thickness uniform from'hub to tip, or with attempts at. variation which have been. exceedingly diflicult to attain. But welding together or other methods of connecting two ormore formings to make up a complete propeller have been sources of weakness and added weight, and have caused trouble in the operation of the propeller. These troubles are particularly manifest at the extreme high speeds at which. aeroplane propellers are required to W k- They h e resulted thus far in Gil complete failure of propellers that have been so constructed, so that the only successful propellers produced for aeroplanes up to the present time have been those made of wood, or those made of molded material reinforced with wires, or otherwise.

In producing the tubular propeller in accordance with the present invention, any one of several machine methods may be employed, although 'I prefer the method 1nvolving the use of a lathe with a su table tail stock center zpdapted to be thrown ver sufficiently to produce the necessary taper and to oflset the center in the blank to produce circumferentially tapered walls, and with the drive f om the opposite end of the tube or the cen er taken, care of in some flexible manner to allow for misplacement of the tail'stock center.

After t-he blank A (Figures 1 and 2) is obtained, it is spun or otherwise treated to give it. the'desired longitudinal profile, as

suggested in Figure 3, where it has the intermediate cylindrical portion B and reduced ends C. This blank is thentaken and treated to provide theclosed ends D (Figure 4). The middle of the closed tube is next located on op osite sides and two holes, say, one-quarter of an inch in diameter, are drilled at opposite ends of a middle diameter thereof. The tube is now heated at the middle, and a sharp tapered punch or drift is revolved at high speed and simultaneously forced into first one and then the other of the aforesaid diametric bores, until an opening is formed" of suflicient diameter to 7 receive the hub-lining or bushing E which will adapt the propeller'td'be placed upon the shaft which is to carry it, a suitable kgy-way being also out, if desired, in the wall of the hole thus formed. In using the tapered punch or drift the displaced metal of the walls of the tube will be projected inwardly r to provide inwardly extending flanges or cylindrical walls F of the opening formed, and serve to secure the hublining or bushing E in position after the hub or lining is fitted in the opening pro- "ided as described. A number of holes may be drilled and tapped into the joint between the hub-lining and the surroundin walls, and close fitting screws introduced t ereinto and finished off flush with the surface. If necessary, these joints can be brazed in addition. A short arbor G is next fitted to the bore of the hub for use in locating the leading andtrailing edges and aerofoil sections.

Since the swaging operation in developing the longitudinal taperin the blank and closing the ends has increased, the thickness of the jswaged-seotions, whereas it is desir-- able to have the thickness gradually reduced from the middle toward theends and also; to; have it -greater in the -por-' tion.: hich is.:to.=.ibrm...thef1eeding' edge blade beyon the middle tapers from a side 9 which will ultimately constitute the leading edge of the blade to the side k which- Will constitute the trailing edge; such edges being in'the blank, as in the ultimate propeller, on opposite sides of the two blades.

For convenience in accurately performing the turning operation to regulate the thickness and distribution of the metal of the walls, the tube of Figure 4 may be mounted in a steady rest at the middle of the blank,

while each end is successively off-centered to receive the tail stock center, so that on being revolved it will have an eccentric swing around its true axis, and more stock will be taken from the trailin the leading edge, and the atter willbe left the-thicker. The tail stock is also off-centered toward the cutting tool for the purpose of removing more stock at the tip than at the hub portion,-where little or none need be removed. The blank may be conveniently driven in the lathe bymounting it in a tube of considerably larger diameter secured to the face plate orlarge chuck of the lathe; and drivin the wor at a point hear the middle or ub portion by suitable flexible driving means; By this method the free .end of the blank next to the'head stock would be able to follow its own eccentric path due to the double offsetting at the tail stock end. When the tube is properly mounted .in the lathe a single cut is taken starting at the tip with a heavy cut and running out to nothing, or clearing. the blank entirely on reaching the points a, c,'or d, d, ofthe mid:

'dle orhub portion. This operation is repeated, as stated, by reversing the blank and off centering the opposite end, care being taken to either advance or retard the setting according to whether the propeller is to be for right hand or left handdrive.

edge than from ioo After removing the surplus stock from the blank, the latter is removed fromthe lathe and placed in a heavy two-part. metal. molding die, H, I, being located therein by means of the short temporary arbor G introduced into its hub opening. The cavity of this die. has the" recise shape of the ultimate propeller to be produced. The' two parts Hand I of the dies are brought together upon the'bla'nk by suitable pressure apparatus, the blank being heated if necessary,- and a suitable fluid pressure being introduced into the hollow blank at sutficient pressure to cause its walls to conform snugly to the cavity of the die and assume the precise shape desired; admission of the fluid being provlded for through a channel'K in the arbor, registering with port L previously drilled in the hub, 01' by other suitable means, or by steam or expanding filler.

I claim:

1. The art of producing a propeller blade, which consists in spinning the metal of a tube to close the end thereof at approximately the end of the blade to be formed,

varying the perimetrical dimensions of the tube to correspond with those of the blade to be formed, and pressing the resultant work-piece into the shape to be given the blade.

2. The art of producing a propeller blade, which consists in closing the end of a tube at a point corresponding approximately to the length of the propeller blade to be .formed, varying the thickness of the tube circumferential] at different portions of said tube towar its outer end to correspond with the thickness of the wall of the blade to be produced, and then pressing said end into the shape of blade desired. with the thick and thin portions of the walls corresponding {3(1) she leading and trailing edgesof the 3. The im rovement in the art of constructing a b ado for a propeller, which consists in s inning the metal of a tube to close an end t ereof at a point corresponding approximately to the end of the blade to be produced, dressin the metal of the tube to taper it from its mner end toward its outer end and also to vary the thickness of its wall circumferentially, and pressing the resultant work-piece into form corresponding to the vblade to be produced, with the thick and thin portions of the wall corresponding to the leading and trailing edges of the blade.

4. The improvement in the art of constructing blades for propellers, which consists in flowing the metal of a tube to close an end thereof at a point corresponding to the end of the blade to be produced, dressing the metal of the tube to taper it from its inner end toward its outer end, and about an axis displaced from the longitudinal axis of the tube to taper the metal of the Wall from the art thereof which is to form the leading e ge of the blade to the part thereof which is to constitute its trailing edge, and pressing the resultant work-piece into form corresponding to the blade to be produced.

Signed at San Francisco, California; this 6th day of November, 1920.

RALPH WI SHON. 

